The grand opening of Apple's store in New York City's Grand Central Terminal last year.Photo by Sarah Tew/CNET

Apple's retail stores have once again nabbed the top spot when it comes to sales per square foot.

According to research firm RetailSails, compared with more than 200 chains in 15 different retail genres, Apple brought in the most money per square foot at its stores during the year.

Photo by RetailSails

According to the rankings (seen right), Apple made $6,050 per square foot during 2012, a little more than twice that of the runner-up, jewelry maker Tiffany & Co., which brought in $3,017 per square foot. By comparison, RetailSails pegged Apple for $5,626 per square foot in its 2011 listing, in which Apple also led the field.

Despite topping the list for highest sales per square foot, Apple did not top a related list from RetailSailes tracking the highest sales per store. That honor went to Costco, with Apple coming in at ninth place, just below BJ's Wholesale and above Village Super Market. Dropping off the list from its spot at number 10 last year was big box retailer Best Buy, which is currently in the midst of restructuring.

Apple's retail empire turned 11 this past May, and has proved to be an integral part of the company's success. Apple closed out its fiscal year at the end of September with 390 stores, and plans to open another 30 to 35 next year. The company's operations are under a closer watch given the recent departure of retail chief John Browett, who Apple last month said no longer works for the company.